The present invention relates to a print control method and apparatus controlling print processing performed in an image forming unit on the basis of a print instruction and print data inputted from an external device, and a computer readable storage medium storing a program realizing the method.
Recently, page printers, such as a laser beam printer and an LED printer, have an advantage of printing a high-resolution image on plain paper, and have become widely accepted on the market. Further, the sizes of paper sheets used for printing widely ranges from A5 size to A3 size.
In order that a page printer can print on various sizes of paper sheets, a plurality of paper holding units (paper feed cassettes) which respectively store paper sheets of different sizes are provided, and an image forming unit of the page printer prints on a paper sheet fed from one of the plurality of paper holding units.
In this case, a user designates the size of a paper sheet to be used for printing to the printer from an external device, and the printer feeds a paper sheet from one of the plurality of paper holding units which corresponds to the designated size, then performs print processing. If there is no paper holding unit for holding paper sheets of the size designated from the external device, the user has to change a paper sheet holding unit which is not currently used into a paper sheet holding unit which holds paper sheets of the desired size. Such troublesome work for changing paper holding units may be omitted by providing as many paper holding units for different sizes of paper sheets as they may be used for printing.
However, as the number of the paper holding units increases, the size of the printer increases accordingly. Furthermore, by increasing the number of paper holding units, the volume occupied by the paper holding units with respect to the overall size of the printer also increases, which lengthens a conveyance path of a paper sheet from each of the paper sheet holding unit to the printing position where printing is performed on the paper sheet by the image forming unit.
In addition, since the conveyance path is lengthened, in order to increase the throughput, paper feed operation for the next page needs to be performed while printing a preceding page.
Further, when the distance from the paper sheet holding unit to the printing position is far longer than the length of the paper sheet in the conveyance direction, in order to achieve a desired throughput, paper sheets to be used to print a few pages later have to be fed while printing a page.
As described above, by increasing the number of paper holding units, the distances from the paper holding units to the printing position are lengthened. As a result, while a printing apparatus is printing a page, an image processing apparatus (a host computer or an apparatus for controlling the printing apparatus) which sends image signals to the printing apparatus has to designate the paper to be used for printing print data of a few pages in advance.
Consequently, interfacing control between the image processing apparatus and the printing apparatus becomes complicated. For example, as many paper feed instructions (or paper feed designation signals) as there are paper sheets that can be placed between the paper sheet holding units and the printing position have to be prepared in advance, and the image processing apparatus has to send each paper feed instruction (or each paper feed designation signal) to the printing apparatus at proper timing while the printing apparatus is printing a page.
Further, normally, the image processing apparatus has to receive an acknowledge status or an acknowledge signal corresponding to each paper feed instruction for confirming whether or not the paper feed instruction is accepted by the printing apparatus. Furthermore, the image processing apparatus has to check which acknowledge corresponds to which paper feed instruction. Thus, the above control is very complicated.
The present invention has been made in consideration of the above situation, and has as its object to provide a print control method and apparatus capable of designating paper feed operation in advance to a printing apparatus in a simple manner without putting extra load on communication control of an external device and the print control apparatus, and a computer readable storage medium storing a program realizing the method.
It is still another object of the present invention to provide a print control method and apparatus capable of realizing high-throughput print processing while confirming a transition state of a printing apparatus in response to a paper feed instruction sent in advance, and a computer readable storage medium storing a program realizing the method.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.